There are conventional inkjet recording devices each of which records images by, while moving a recording head that discharges ink and has a plurality of nozzles and a recording medium relative to one another, discharging the ink to the recording medium from the nozzles of the recording head. Nowadays, as to this type of inkjet recording device, in order to meet a demand on increase in recording speed, a long head unit(s) (recorder(s)) in which recording heads are arranged at different positions in the width direction that intersects the direction of the above relative movement is formed, and a technique of discharging ink from nozzles disposed in each of the recording heads of the long recorder(s), thereby recording images, is used.
In inkjet recording devices, variation in ink discharge amount among nozzles of a recording head leads to decrease in image quality. Further, if the number of recording heads is two or more, variation in the discharge amount among the recording heads tends to occur. To deal with this, there is a technique of performing adjustment to suppress variation in the amount of ink to be discharged from nozzles of recording heads, thereby suppressing decrease in quality of recorded images.
For example, there is disclosed in Patent Document 1 a technique of controlling a drive operation for a portion(s) of an image recorded by recording heads of a recorder on the basis of image data having a predetermined density, the portion where the actual density departs from the overall average range.
Further, there is disclosed in Patent Document 2 a technique of controlling a drive operation for each recording head such that at a joint in nozzles of recording heads, the actual density value of an image having a predetermined density recorded with ink discharged from the nozzles of one recording head matches the density value of the image having the predetermined density recorded with the ink discharged from the nozzles of the other recording head.